This invention relates to a flexible tube of an endoscope.
An endoscope is provided with a flexible tube which is inserted into a human body cavity. In order to obtain the flexibility, the flexible tube includes a tubular spiral made of a metal band wound in helical fashion. In order to maintain the wound shape of the metal band of the tubular spiral, a meshwork tube is provided around the tubular spiral to cover the tubular spiral. A resin sheath is adhered to the outer surface of the meshwork tube, thereby to surround the meshwork tube.
However, when the flexible tube is bent, a stress is applied to the resin sheath at the bent portion of the flexible tube. Therefore, the resin sheath may be separated from the meshwork tube, which causes buckling of the resin sheath. Thus, the durability of the flexible tube may be lowered.
Further, since a stress is also applied to the resin sheath at the bent portion of the flexible tube, the meshwork tube may be separated from the tubular spiral, so that the wound shape of the metal band may not be maintained. Thus, the flexibility of the flexible tube may be lowered.